159.15

[TinEar]

The 159.15 D.C. Police freq has always been listed as Citywide - a simulcast of TG16624 - and that's what the database shows it to be. However, every time I run across it, it is simulcasting District 1, TG16400 - as it is tonight. Is this a change? Do they switch it around occasionally? Is it only coinicidence that it's District 1 each time I tune into it?

 

[Samuel]

Often times, especially at night, 1D and Citywide are patched. MPD has been doing this as long as I can remember.

 

[TinEar]

Thanks Sam. Last night I had one radio on TG16400, one on TG16624 and one on 159.15. Over the course of about three hours, all the traffic on 159.15 was from 1D and nothing from Citywide. I'll have to do more listening to see when they add Citywide to the mix. It's difficult to listen to both the trunked traffic and the simulcast on 159.15 because the 159.15 traffic is about 1/2 second ahead of the talkgroup so it's like listening to an echo.

 

[Dewey]

Hi TinEar

159.15 is indeed the VHF simulcast of Citywide 1. As previously and correctly posted, you will find 1D and Citywide patched together during "low traffic" times to save on dispatchers. This goes way way way back into the old conventional days when all the districts would patch together on midnights... CW/1D, 2D/3D, 4D/5D, 6D/7D.

I think the reason you can't tell is because of the way the scanners seem to handle patches (or at least DC's patches, but I've heard likewise about other areas also). I notice that when a patch is enabled, the scanner will only receive the channel that originated the patch, the channel that is patched in will not be detected. When DC simulcasts priority lookouts, sometimes they are done on a single simulcast talkgroup, and other times, the other districts are patched to the dispatcher broadcasting the lookout. When the simulcasts are made through the patching method, I only hear them when the scanner stops on the district that created the patch. I've confirmed this by watching the patch on Trunker.

Dewey

 

[TinEar]

Very nice explanation Dewey. Thank you.